The disclosure of Japanese Patent Application No. 2000-136957 filed on May 10, 2000 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an operation control apparatus and an operation control method. More particularly, the invention relates to an operation control apparatus installed in a vehicle for controlling the state of running of the vehicle and an operation control method for controlling the state of running of a vehicle.
2. Description of the Background
Normally, a drive power generating apparatus installed in a vehicle for generating drive power for the vehicle performs a control regarding generation of drive power while inputting detection signals from various sensors for detecting the state of operation of the vehicle, the state of driving of the power generation apparatus, etc. If an abnormality occurs to a sensor that outputs a detection signal, the power generating apparatus becomes unable to normally execute the control for generating drive power by using the detection signals.
For example, Japanese Patent Application Laid-Open No. SHO 64-24145 discloses an art related to the invention. In a method disclosed in the aforementioned patent application, a plurality of systems of sensors for detecting predetermined operation characteristic quantities regarding the vehicle are provided. If an abnormality occurs in a sensor, the detection signal from another sensor is used to drive the drive power generating apparatus, and furthermore, the output characteristic of the power generating apparatus is changed in order to cause a driver to feel the occurrence of an abnormality. For example, an air-fuel ratio control and an ignition timing control regarding a gasoline engine, that is, a drive power generating apparatus, are performed by using detection signals from an air flow sensor that detects the amount of intake air supplied into the engine. If the air flow sensor has an abnormality, the detection signal from a throttle sensor for detecting the degree of opening of a throttle valve is used instead of the detection signal from the air flow sensor, in order to perform the control. Furthermore, when the air flow sensor has an abnormality, the output characteristic of the engine is changed from the characteristic exhibited during a normal state, that is, the air-fuel ratio control and the ignition timing control are changed from those performed during the normal state, thereby causing a driver to actually feel the occurrence of a abnormality. This construction makes it possible to continue running the vehicle and to inform the driver of the occurrence of an abnormality.
However, even when a driver is thus caused to actually feel the occurrence of an abnormality, the driver may continue running the vehicle since a sufficient running performance is secured by the control that uses output signals from a sensor that is different from the sensor used during the normal state. The continuation of the running of the vehicle when a sensor regarding the control of the drive power generating apparatus, such as the engine or the like, has an abnormality, is not desirable in terms of safety because if another abnormality occurs in the vehicle, the vehicle is possible to fail to appropriately respond to the abnormality.
As a countermeasure taken when an abnormality is detected in a sensor regarding the drive control of the vehicle, it is conceivable to determine that a normal control is impossible and to prohibit the running of the vehicle. However, if an abnormality is detected during the running of the vehicle, prohibiting the running of the vehicle may make the vehicle fail to be controlled apporoprately.
Accordingly, it is an object of the invention to provide an operation control apparatus and an operation control method for securing sufficient safety of a vehicle even at the time of a specific kind of abnormality, such as an abnormality related to a control of a drive power generating apparatus.
Each of an operation control apparatus and an operation control method in accordance with a first mode of the invention is incorporated in a vehicle and, when controlling the state of running of the vehicle, controls a drive power generating apparatus so as to generate drive power in accordance with a request for an increase in the drive power to be outputted via an axle of the vehicle. When an abnormality of the vehicle is detected, the drive power generating apparatus is controlled in a during-abnormality control mode corresponding to the content of the abnormality.
According to the first mode of the invention, when a specific kind of abnormality is detected in the vehicle, a control mode corresponding to the kind of the detected abnormality is executed among a plurality of pre-set xe2x80x9cduring-abnormalityxe2x80x9d control modes. Therefore, even at the time of occurrence of an abnormality, a vehicle drive power is secured in accordance with the kind of the abnormality that has occurred.
The during-abnormality control mode is a control mode which restricts changes in the drive power in accordance with a drive power increasing request, in comparison with a state where the abnormality is not detected.
This construction reduces the accelerating performance of the vehicle at the time of occurrence of an abnormality, in comparison with a normal level. Therefore, it prevents excessive acceleration of the vehicle having an abnormality, and improves the safety of the vehicle running with an abnormality being present.
Furthermore, the during-abnormality control mode may prohibit the vehicle from accelerating regardless of the drive power increasing request, after the speed of the vehicle reaches a specific speed.
Therefore, at the time of occurrence of an abnormality, the vehicle speed does not exceed the aforementioned specific vehicle speed. Hence, this construction prevents undesired high-speed running of the vehicle having an abnormality, and improves the safety of the vehicle running with an abnormality being present.
Furthermore, the during-abnormality control mode may allow a drive power corresponding to the drive power increasing request to be generated until the speed of the vehicle reaches the specific speed, provided that the speed of the vehicle occurring when the abnormality is detected is at least a predetermined speed.
This construction improves safety at the time of an abnormality during high-speed running.
Furthermore, the during-abnormality control mode may allow the vehicle to run in accordance with the drive power increasing request up to a predetermined speed that is beyond the specific speed of the vehicle, provided that at least one of certain conditions is met, the conditions including an elapsed time following detection of the abnormality and a travel distance following detection of the abnormality.
Therefore, within a predetermined time or a predetermined travel distance following detection of an abnormality, the running of the vehicle that reflects a driver""s intention can be performed up to the predetermined vehicle speed that is beyond the specific vehicle speed. Thus, a sufficient protective action can be taken.
Still further, the during-abnormality control mode may be a control mode of generating the drive power in the drive power generating apparatus by using a portion capable of being normally driven when the abnormality occurs, and of changing the drive power in accordance with the drive power increasing request.
This construction makes it possible to generate the drive power by using the portion capable of being normally driven, and to perform the running of the vehicle that reflects a driver""s intention. Therefore, a best-possible drive power for a protective action can be secured, and safety at the time of occurrence of an abnormality can be improved.
Still further, the during-abnormality control mode may restrict the drive power of the vehicle stepwise based on at least one of an elapsed time following detection of the abnormality and a travel distance following detection of the abnormality.
This construction secures a further sufficient drive power until the predetermined time elapses following detection of an abnormality or until the vehicle runs the predetermined distance following detection of an abnormality. Therefore, a protective action can be easily taken, and the safety at the time of occurrence of an abnormality can be improved. Furthermore, by restricting the drive power of the vehicle in a stepwise fashion, the construction deters longer-than-necessary continuation of the running of the vehicle with an abnormality being present. Thus, safety of the vehicle can be improved.
Still further, a plurality of detectors that detect a specific quantity of displacement regarding the vehicle may be provided, and the abnormality corresponding to the during-abnormality control mode of restricting the drive power of the vehicle stepwise may be an abnormality that occurs in at least one of the detectors, so that if an abnormality occurs in at least another one of the detectors it is impossible to detect the abnormality.
Therefore, if the detected abnormality is an abnormality that occurs in at least one of the detectors for detecting the specific quantity of displacement regarding the vehicle so that if an abnormality occurs in at least another one of the detectors it is impossible to detect the abnormality, then the drive power of the vehicle is restricted stepwise. Hence, it becomes possible to substantially prevent an event that if an abnormality occurs in the other detectors, the driver continues driving the vehicle without being aware of the abnormality. Thus, safety of the vehicle can be improved.
Still further, the during-abnormality control mode may be a control mode of outputting a sufficiently small drive power that allows the vehicle to be moved via the drive power generating apparatus regardless of the driver""s drive power increasing request.
This construction makes it possible to secure a drive power that is needed to move the vehicle. Even if, depending on the kind of abnormality, it becomes difficult to perform a control that reflects a driver""s intention, the vehicle can be moved to a safe place. Thus, safety of the vehicle can be improved.
Each of an operation control apparatus and an operation control method in accordance with a second mode of the invention is incorporated in a vehicle and, when controlling the state of running of the vehicle, controls a drive power generating apparatus installed in the vehicle for generating a drive power of the vehicle, detects a specific kind of an abnormality in the vehicle and, after detecting an abnormality, restricts the drive power of the vehicle stepwise.
According to the second mode of the invention, the restriction of the drive power is performed stepwise after an abnormality is detected. Therefore, at the time of occurrence of an abnormality, a further sufficient drive power can be secured. Hence, a protective action can be taken more safely at the time of occurrence of an abnormality.
The operation control apparatus of the second mode may further include a plurality of detectors that detect a specific quantity of displacement regarding the vehicle, and the specific kind of abnormality may be an abnormality that occurs in at least one of the detectors so that if an abnormality occurs in at least another one of the detectors it is impossible to detect the abnormality.
Therefore, if the detected abnormality is an abnormality that occurs in at least one of the detectors for detecting the specific quantity of displacement regarding the vehicle so that if an abnormality occurs in at least another one of the detectors it is impossible to detect the abnormality, then the drive power of the vehicle is restricted stepwise. Hence, it becomes possible to substantially prevent an event that if an abnormality occurs in the other detectors, the driver continues driving the vehicle without being aware of the abnormality. Thus, safety of the vehicle can be improved.
Furthermore, the drive power may be restricted based on at least one of an elapsed time following detection of the abnormality and a travel distance following detection of the abnormality.
This construction secures a further sufficient drive power until the predetermined time elapses following detection of an abnormality or until the vehicle runs the predetermined distance following detection of an abnormality. Therefore, a protective action can be easily taken, and the safety at the time of occurrence of an abnormality can be improved.
The modes of the invention are not limited to the above-described operation control apparatus. Another mode of the invention is a vehicle equipped with an operation control apparatus in accordance with the invention. This vehicle achieves advantages as stated above, for example, advantages of securing a further sufficient drive power at the time of occurrence of an abnormality, and making it easier to take a protective action, and deterring longer-than-necessary continuation of the running of the vehicle with an abnormality being present, etc.